Analyzing Rookie Pitchers Part 1

This season, this short, crazy, and insane season has seen a lot of rookie pitchers. With all of the call ups, this has been one of the more compelling MLB seasons we have seen in a long time. It seems like every week there are new pitchers being called up to grab a spot start. Pitchers who haven’t even reached the AAA level. Most importantly pitchers that we have been waiting a long time to see. There will be two parts to this article as we will analyze some of these rookie pitchers, how they are performing, and what their future holds.

Dane Dunning

Before having Tommy John surgery in 2019 Dane Dunning was a borderline top 100 prospect. He had a deep arsenal with above-average command and of course, wears those fashionable glasses. But, when it comes to pitchers coming off Tommy John it is tough to tell how they will bounce back leaving him as a big question mark coming into 2020. Dunning has been called up for four starts and so far has produced an awe-inspiring 2.70 ERA, 2.78 FIP, and 17.3 K-BB%.

So far Dunning has shown a unique ability to produce weak contact and high strikeout potential. He boasts a 53.8 GB%, 25.9 K%, 15.4 SwStr%, and 5.7 Barrel%. All of these marks are above average and again exemplify what every pitcher tries to accomplish. Creating weak contact as well as strikeouts. 

Dunning mainly relies on a sinker, four-seam, and slider for his repertoire. The four-seam hasn’t been great mainly due to command but it does get some decent horizontal movement. If he can fixate it towards the top of the zone more it will be a fine third pitch. His slider has a late vertical break and really acts like a curveball. Albeit a small sample size but it currently holds a 45.8 O-Swing%, 26.8 SwStr%, and 61.5 GB%. Overall this pitch looks like one of the better sliders in the league because of its otherworldly numbers. Dunning’s main pitch is a sinker which also has solid movement and has performed really well, but it looks like regression might be in the works. Its .167 batting average against (BAA) comes with an expected .356 BAA. Much like his four-seam, he leaves it over the plate too often.

When it comes to 2021 Dunning is an intriguing pitcher. You can’t deny his success so far but with what looks like iffy command and small sample size it’s hard to make an assessment. You also have to consider that the White Sox rotation is a little crowded and Michael Kopech comes back next year.

Tarik Skubal

The left-handed former reliever in the Tigers system struck a chord in A+ and AA ball last year. In AA he pitched to a 2.13 ERA, 1.26 FIP, and ludicrous 48.2 K%. This certainly propelled the Tigers into giving him a shot in the rotation. Sadly his success hasn’t transferred over into the majors because in five starts Skubal has a 7.27 ERA.

That 7.27 ERA is a little deceiving though. For some reason unbeknownst to me, the Tigers decided to let him debut against the White Sox. An offense that has killed left-handed pitchers all year. He of course fell flat on his face pitching just two innings and allowing four earned runs. Throughout the next three starts, he would perform well producing a 2.70 ERA and 4.08 FIP. But then to only be blown up once again by the Cardinals. This can be typical of any rookie pitcher as they always tend to struggle. All in all a lot of ups and downs with Skubal so far this season.

Here is the big issue with Skubal and why you need to be wary of him coming into 2021. He was supposed to be a strikeout pitcher. A 22.7 K% with an 11.0 SwStr% doesn’t move the needle. Plus his two breaking pitches (slider and changeup) both have sub-par SwStr%’s. Tack on all of the hard contact he has let up and Skubal is definitely someone you shouldn’t have confidence in.

Brady Singer 

If you watched Brady Singer’s last start you’d probably be impressed with a rookie pitcher who has come from AA ball. He flirted with a no-hitter against the Indians battling through eight innings allowing one hit and striking out eight. Overall Singer has been lackluster and the pitcher we knew he would be. 

Singer relies on weak contact featuring a plus slider in his arsenal. The 52.9 GB% and 4.3 Barrel% have been impressive but there are some underlying concerns. His wOBAcon sits a .386 which is above average and means he is giving up quality contact. Diving further, Alex Chamberlain’s dERA for Brady Singer is 4.75. Alex’s dERA is a conversion of wOBA to ERA. Basically meaning Singer allows quality contact. You can read about it here.  

The argument for Singer’s lack of success is his tough schedule which is certainly true. Singer this season has faced the White Sox twice and the Twins three times. Even so, Singer has a lot of red flags, and looking at a pitcher who barely creates weak contact with no strikeout upside is seemingly a waste of time

Triston McKenzie 

McKenzie is a six-foot-five tall lanky pitcher who dominated in 16 starts in AA last year. Overall in his first five starts in the MLB, McKenzie holds a 3.91 ERA. When Triston McKenzie was called up I remember running to the television to watch his debut. In his first start, he showed a lot of poise and absolutely shredded the Tigers offense. The main worry seemed to be his command. He left his fastball over the middle of the plate a lot in that start and seemed to get very lucky. 

McKenzie relies on his four-seam as he throws it over 55% of the time. This means leaving this pitch over the middle of the plate probably won’t bode well for him. Even with command issues, his four-seam has still produced a positive pVAL and an above-average SwStr%. Imagine if he can hit the top of the zone often, how good this pitch can be. Well, the problems don’t stop there, as Ray Butler (owner of Prospects 365) pointed out on Twitter McKenzie’s fastball velocity has been dwindling with each start.

Triston McKenzie Fastball Velocity
Game Date Four-Seam Velocity
8/22 94.6
8/28 93.4
9/2 92.8
9/8 92.5
9/13 92.2


Velocity rapidly decreasing is never a good thing. In his first two starts where his velocity was over 92 MPH, he produced a 2.70 ERA and .147 batting average against. In the three starts since it dipped below 93 MPH, he has put up a 4.70 ERA and .170 batting average against.

While yes the fastball is worrisome McKenzie still has a stellar slider and curveball. Both of these pitches have produced a negative wRC+ against and a 0.00 ISO. That is extremely impressive. If he can work on his fastball command and the Cleveland Indians can feed him some of their magic sauce you can expect McKenzie to become a valuable pitcher for 2021.


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Uncle Spikemember
3 years ago

In regards to McKenzie, when you see velocity diminishing like that, is that a sign of a potential injury or is that typically fatigue related?

JD, Too
3 years ago

Any reason you’re leaning fatigue or is it more that you’re hoping it’s just fatigue?